1. Field of the Invention
The invention relates generally to fire extinguishing apparatus useful in a chimney to extinguish chimney fires and particularly to a retrofittable cap for existing chimneys which can be placed over the upper exposed end of a chimney liner to be actuable under conditions of unusually high temperatures, such as occur during a chimney fire, to extinguish combustion within the chimney.
2. Description of the Prior Art
Substantial property losses occur each year due to fires which originate in the chimney of a fireplace, these fires typically resulting from the combustion of an accumulation of combustible materials on inner walls of a chimney. These accumulated combustible materials are the by-products of the burning of wood and other materials in the fireplace. Even thorough cleaning of a chimney does not guarantee protection against a chimney fire since these combustible materials accumulate rapidly and it is difficult to visually inspect a chimney to determine the presence of dangerous accumulations. Given the prevelance of chimney usage in rural areas and the resurgance of the use of wood heat in recent years, particularly in residences, it is perhaps not surprising that chimney fires account for a large percentage of fires in residences and likely account for over 15% of serious fires in rural areas. Due to the extreme heat and rapidity with which chimney fires burn, it is usually the case that the entire structure is lost. While the need has long existed to provide a solution to this substantial problem, no previous devices have been available which have been effective and have been capable of being retrofit to existing fireplace and chimney structures without the need for modification of the chimney structure itself. U.S. Pat. Nos. 314,121 to Gilman; 1,352,255 to Emerson and 2,270,073 to Merry are examples of prior sturctures which disclose the use of damper devices adapted to close in the event of a fire in a chimney structure to reduce oxygen flow to the fire. In these patents, a fusible element is employed which is fused by the heat of the fire to result in the closing of the damper. However, the structures shown in these patents and in other prior art require modification of the basic structure of the chimney and/or fireplace and must be installed in the chimney or fireplace at the time of construction. The need has thus been long felt for apparatus which can be retrofit to existing chimneys without modification of the basic structure of the chimney. Further, the need has further been felt for apparatus for extinguishing chimney fires which reduced the damage to the interior of a building caused by smoke which occurs even though the chimney fire itself may be extinguished. The present invention provides apparatus capable of extinguishing a chimney fire and which in a preferred embodiment allows a reduced air flow through the chimney which is insufficient to support combustion but which reduces the amount of smoke damage which can occur during a chimney fire even when the fire is extinguished. The present invention provides apparatus which can be simply placed on the upper exposed end of a chimney liner without modification of the chimney, the liner or the fireplace and which acts without additional assistance to extinguish fires within the chimney which occur as a result of the burning of accumulated combustible materials on the inner walls of a chimney structure.